ASSESSMENT OF EXCESS FLUID DISTRIBUTION IN CHRONIC-HEMODIALYSIS PATIENTS USING BIOIMPEDANCE SPECTROSCOPY

Sodium and water homeostasis is abnormal in hemodialysis (HD) patients , however, the distribution of the excess fluid (extracellular vs. int racellular) has not been fully characterized. We studied the distribut ion of fluid using bioimpedance spectroscopy to determine if HD patien ts have an excess of fluid in any specific compartment relative to con trols. Dual-energy x-ray absorptiometry was used to measure lean body mass and bone mineral content. The resistive index (RI) for extracellu lar water volume (RI(ECW)), was significantly increased in patients pr e-HD when corrected for bone mineral content (RI(ECW):BMC) (pre-HD, 19 .0 +/- 3.3; controls, 15.8 +/- 1.7 cm(2)-ohms(-1)-kg(-1); P < 0.01). T his value decreased to the control range following HD (15.2 +/- 2.5 cm (2)-ohms(-1)-kg(-1)). The intracellular water volume to bone mineral c ontent (RI(ICW):BMC) was not different between controls and HD patient s. These data suggest that hemodialysis patients carry their excess fl uid volume primarily in the extracellular compartment and that bioimpe dance spectroscopy coupled with a stable measure of lean tissue such a s bone mineral content can determine the degree of relative excess hyd ration.